I don't care much for many classics, but I would consider Hitchhiker's Guide to the Galaxy and Ender's Game to be classics.
Not having read these classics would mean that you would miss references to them in today's culture.
So maybe being less 'cultured' just means you wouldn't understand if...
Can we decide objectively that something fits a given definition?
If someone gives me a definition for a square that states that a square is
only two-dimensional, I can state that a given three-dimensional object is not a square completely objectively.